1. Field of the Invention
The present invention relates to electrical connectors for power cords and the like. More particularly, the present invention relates to rotatable connectors that freely rotate.
2. Description of the Prior Art
Electrical power cords are used in many different applications to conduct electricity from a power source to an electrically powered apparatus. Power cords are used in connection with all types of electronic equipment such as stereos and computers, portable electric appliances such as those typically found in a kitchen, hand-held power tools and the like. Power cords can be formed having virtually any length, from one foot or less to hundreds of feet. Those longer cords, often referred to as extension cords, allow an apparatus connected to the cord to be more portable, as the use of the device will not be restricted by or limited to the location of the power source. Thus, it will be appreciated that power cords serve a number of useful functions in connection with many different types of devices.
One significant drawback associated with power cords is that such cords often tend to twist or become knotted during use. This problem is especially prevalent in connection with equipment that is continuously moved around relative to the power source, such as typical hand-held power tools. A tangled or twisted cord results in a reduction of the effective length of the power cord, which limits the useful range of the tool coupled to the power cord. This requires that the user manually untangle the cord, which is inconvenient, annoying, and time-consuming.
In addition, continual twisting or knotting of a cord can cause stress or strain on the cord. The conductors housed inside the cord may become crimped or may even break, resulting in a shortened useful life of the power cord.
A number of swivel connector designs have been proposed by others in an attempt to overcome the above-described disadvantages. One of those prior art devices includes a plurality of bearings and interposed insulating washers in a housing. A form of that device is disclosed in U.S. Pat. No. 1,649,276 to Adam. The bearings include inner and outer races connected to electric leads from a pair of severed power cord segments. The ends of the electric leads are sandwiched between the inner races and the adjacent insulating washers to effect an electrical connection with the inner races. It will be appreciated that any relative displacement of the bearings and washers will likely create a short circuit, as the electric leads are not securely connected to those races.
Another rotatable, multiple lead connector found in the prior art includes a receptacle with a conically shaped internal bore to receive a generally frusto-conically shaped plug. A form of this device is disclosed in U.S. Pat. No. 3,193,636 to Daniels. The receptacle includes a plurality of radially inwardly projecting, V-shaped conductive contacts at axially and circumferentially spaced apart locations. Outwardly projecting, conductive contact rings with V-shaped grooves are formed on the periphery of the plug to engage the contacts and make electrical contact while allowing the plug to be rotated relative to the receptacle as the V-shaped tips ride in the V-shaped grooves. Such a device requires a rather elaborate and detailed construction. Furthermore, the device is designed such that the points of electrical contact are rotated relative to each other, which over time may cause a wearing down of one of the components such that electrical contact is lost.
Yet another prior art swivel device includes male and female connectors formed with complementary concave and convex circumferential regions to establish electrical contact and to provide for relative rotation. A form of this device is disclosed in U.S. Pat. No. 5,409,403 to Falossi et al. The concave and convex sections are conductive and electrically connected to electric wires from a pair of power cord segments. Use of this device results in relative rotation between the electrical contacts which over time may cause a wearing down of the contact surfaces and thus an open circuit. In addition, if the concave and convex portions are constructed such that they make a strong engagement to resist disengagement, then relative rotation will likewise be resisted by those portions. If, on the other hand, the concave and convex portions are configured so that relative rotation is not resisted, then the connection between those portions will not be very secure and may result in unwanted separations causing an open circuit. Thus this type of device suffers from a number of design defects.
Accordingly, it will be understood that there continues to be a need for a rotatable electrical connector which is relatively simple to construct and which provides secure electrical connections while permitting free rotation. The present invention completely addresses these needs.